Conventionally, it is known to attach a semiconductor device to a cooling heat sink, for example, by screws. For example, in JP-A-2007-165426, screw fastening portions are provided in the vicinity of ends in a long side direction of a semiconductor device and the semiconductor device is fixed to a cooling heat sink by screws.
However, in a case where a semiconductor device and a cooling heat sink are fixed by screws in the vicinity of ends in a long side direction as described in JP-A-2007-165426, a forcing pressure may be insufficient at a center portion of the semiconductor device far from the screws, the semiconductor device and the cooling heat sink may be not closely in contact with each other, and a heat radiation may be insufficient.